The present disclosure relates to a memory device and a manufacturing method thereof, and more particularly, to a conductive bridging random access memory (CBRAM) device showing a nonvolatile memory behavior by forming a metal bridge and a manufacturing method thereof.
A resistive random access memory (ReRAM) is one of next generation memories being developed for overcoming limitations of DRAMs and flash memories, and gets the spotlight with a simple structure including an oxide film intervened between top and bottom electrodes. A ReRAM implements nonvolatile memory characteristics by adjusting oxygen vacancies in an oxide film prepared between top and bottom electrodes. However, due to low conductivity and difficulty in adjustment of oxygen vacancies, the ReRAM has low current density and low reliability.
In order to complement such a weak point of the ReRAM, a conductive bridging random access memory (CBRAM) is being researched. A CBRAM has a structure in which a solid electrolyte layer is formed between the top and bottom electrodes, and may have a high current density by forming a metal bridge inside the solid electrolyte layer. Such a CBRAM is a device showing a bidirectional switching behavior, which maintains a low resistance state by allowing metal cations to be drifted into the solid electrolyte layer to form a metal bridge according to application of a positive voltage to the top electrode, and maintains a high resistance state by allowing a part of the metal bridge to be cut according to application of a negative voltage.
As a solid electrolyte material, amorphous silicon, copper doped zinc oxide (Cu-doped ZrO2), copper doped silicon oxide (Cu-doped SiO2), Ag—Ge—Se, Ag—Ge—S, Cu2S, Ta2O5, and a polymer, etc., are used. For example, NANO LETTERS 2009, Vol. 9, No. 2 pp. 870˜874 discloses using amorphous silicon as a solid electrolyte material.